st: Blinking message when using _rc

Greetings,
I'm running the program below:
***start***
local M "A B C"
foreach m in `M' {
capture confirm variable `m'_X
!_rc {
quietly count if missing(`m'_X)
if r(N)==_N{
drop `m'_X
display "`m'_X" " dropped"
}
}
capture confirm variable `m'_X
if !_rc {
replace `m'_X="1" if `m'_X=="P"
}
}
***end***
It does the job that I need. But while it is running, I see a black
windows window for just a moment each (literally), that gives me a
message that reads like:
"!_rc { is not recognized as an internal or external command, operable
program or batch file."
Because the program above runs many times, I see that window multiple
times for a moment, like blinking. I can hardly read it the moment I
see it, but I could write it down after running the code many times.
Does anyone have an idea of what that means?
Thanks in advance
Duha
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